Regarding a tool, such as an end mill and a milling cutter, that performs cutting process on a workpiece with peripheral edges, there is a technique of shortening the length of cutting edges that contact a workpiece and accordingly reducing cutting resistance by that much by adopting wave-shaped roughing formed cutting edges or interrupted cutting edges provided with nicked teeth at a constant interval as peripheral edges. In the roughing formed cutting edges and the interrupted cutting edge, the phases of waveforms of adjacent peripheral edges in an axial direction are shifted. The phase shifts are normally set to a constant value obtained by dividing a waveform pitch with the number of edges, and the phases of adjacent peripheral edges are shifted by the constant value. That is, in a cross section vertical to an axis, the phases are shifted by one pitch per round (see FIG. 9 of Japanese Patent Application Laid-Open Publication No. JP 63-34010, and see also page 4, lower right column, lines 3-16, FIG. 3, etc. of JP 63-34010).
In this case, as described above, JP 63-34010 discloses a technique in which phase shifts are specified using a predetermined relational expression to make two or more cutting edges of a same dimension and a same shape appear on a cross-section vertical to an axis, noting that the configuration using phase shifts of a constant value to shift by one pitch per round is not sufficient in extending a tool life and improving processing efficiency. Also, as described above, Japanese Patent Application Laid-Open Publication No. JP 11-27214 discloses a technique in which phase shifts are made irregular because if phase shifts between adjacent peripheral edges are regular, chattering vibration is generated (see also page 3, upper right column, lines 3-11, FIG. 2, etc. of JP 11-27214).
On the other hand, Japanese Patent Application Laid-Open Publication No. JP 2002-233910, in paragraph [0009], etc. discloses a technique of increasing/decreasing waveform pitches and the like at a predetermined cycle because if the waveforms of roughing formed cutting edges or interrupted cutting edges are provided periodically in a constant dimension over a total length of a peripheral edge, chattering vibration is generated.